A recent improvement for adjusting the lip gap of an extrusion die having a flex lip, is described in U.S. patent application Ser. No. 08/936,655, filed on Sep. 24, 1997, now U.S. Pat. No. 6,017,207. In that apparatus, an operator attaches a wrench to a rotatable adjustment spool located near the exit slot, and applies force to rotate the spool to adjust the lip. When the die is in operation, pressure in the flow passageway of the die requires an increased force be applied to adjust the lip gap. In addition, the operator may not be able to make a fine adjustment of the lip gap. Additionally, the location of the adjustment spool may result in the operator being near the hot extrudate, limit the space available for the adjustment, or interfere with the space requirements of other equipment.
Accordingly, it is an object of the present invention to provide a control assembly that allows an operator to adjust the lip, yet be further removed from the exit slot and hot extrudate, for instance, to stand behind the die. In this way, worker safety will be improved, and it will be easier to retrofit existing equipment. It is a further object to provide for fine adjustment of the lip. Moreover, it is an object to reduce the force exerted on a gear assembly used for adjusting the lip. Still further objects and advantages will become apparent from a consideration of the description and drawings.
In accordance with the present invention, an extrusion apparatus includes a flow passageway terminating in an exit slot having a gap and defining an output end of the extrusion apparatus, and the gap is formed in part by a flex lip; and further includes a reciprocally movable member operatively connected to the lip for adjustment of the gap. The control assembly includes a gear assembly operatively connected to the reciprocally movable member (or bar) for reciprocally moving the actuator bar, and includes a shaft connected to the gear assembly and in one aspect of the invention, a handwheel or motor positioned opposite the output end of the extrusion apparatus. In another aspect of the invention, the control assembly includes a shaft disposed generally perpendicular to a recess in which the actuator bar is disposed, and a portion of the shaft is supported by a recess of an end plate of the extrusion apparatus.
In a variation of the invention, a first gear assembly is operatively connected to an end of the actuator bar for moving the actuator bar in a first direction, and a second gear assembly is operatively connected to an opposite end of the actuator bar for likewise moving the actuator bar in the first direction. Beneficially, the first gear assembly and second gear assembly are simultaneously controlled to move the actuator bar in the first direction. Advantageously, as before, an input shaft for a gear assembly is oriented generally perpendicular to the direction of movement of the actuator bar, and an input end of the input shaft extends in a direction opposite to the output end of the extrusion apparatus.